全文获取类型
收费全文 | 395篇 |
免费 | 31篇 |
专业分类
林业 | 20篇 |
农学 | 9篇 |
基础科学 | 1篇 |
41篇 | |
综合类 | 103篇 |
农作物 | 14篇 |
水产渔业 | 20篇 |
畜牧兽医 | 204篇 |
园艺 | 6篇 |
植物保护 | 8篇 |
出版年
2021年 | 13篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 9篇 |
2014年 | 6篇 |
2013年 | 13篇 |
2012年 | 17篇 |
2011年 | 15篇 |
2010年 | 8篇 |
2009年 | 13篇 |
2008年 | 16篇 |
2007年 | 16篇 |
2006年 | 16篇 |
2005年 | 15篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 19篇 |
2001年 | 10篇 |
2000年 | 6篇 |
1999年 | 8篇 |
1998年 | 5篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 11篇 |
1972年 | 9篇 |
1971年 | 5篇 |
1970年 | 5篇 |
1969年 | 8篇 |
1967年 | 3篇 |
1966年 | 4篇 |
1961年 | 4篇 |
排序方式: 共有426条查询结果,搜索用时 93 毫秒
81.
82.
N.E. Gillette C.J. Mehmel J.N. Webster S.R. Mori N. Erbilgin D.L. Wood J.D. Stein 《Forest Ecology and Management》2009
We tested methylcyclohexenone (MCH), an anti-aggregation pheromone for the Douglas-fir beetle (Dendroctonus pseudotsugae), for protection of Douglas-fir (Pseudotsuga menziesii) stands by applying MCH-releasing polymer flakes by helicopter twice during summer 2006 to five 4.05-ha plots in the State of Washington, USA. Five similar plots served as untreated controls. We assessed D. pseudotsugae flight into study plots using baited pheromone traps, and tallied D. pseudotsugae attack rates on all P. menziesii trees in 2005 and 2006. We also measured stand basal area and incorporated that as an explanatory variable in the analysis. Significantly fewer D. pseudotsugae were trapped in treated plots than in control plots, and significantly fewer P. menziesii trees were attacked in treated plots than in control plots. The attack rate in untreated stands was nearly 10 times that of treated plots, and stands with higher basal area were significantly more likely to be attacked by D. pseudotsugae than were stands of lower basal area. Attack rates in 2006 and 2005 were significantly correlated, regardless of treatment. 相似文献
83.
Aleksander Handå Trond Nordtug Stein Halstensen Anders Johny Olsen Kjell Inge Reitan Yngvar Olsen Helge Reinertsen 《Aquaculture Research》2013,44(4):645-656
Feed requirements were estimated from specific growth rates in standardized soft tissue dry weight (SGRDW’) and atomic O:N ratios for mussels fed seven rations of microalgae (5–735 μg C h?1 ind?1) at 7 and 14°C respectively. The mean oxygen consumption and ammonia‐N excretion rates were significantly higher at 14°C (0.29 μg O2 and 27.3 μg N ind?1 h1) compared with those at 7°C (0.16 μg O2 and 11.4 μg N ind?1 h?1) (P < 0.05), resulting in O:N ratios between 3 and 45 at 7°C and 7 and 28 at 14°C. Low O:N ratios indicate protein catabolism and an unfavourable condition, whereas high ratios indicate that carbohydrate is the primary energy source. The measured SGRDW’ suggests minimum feed requirements of ~240 and ~570 μg C ind?1 h?1 for weight maintenance at 7 and 14°C, with corresponding O:N ratios of 24 and 16, respectively, indicating a more stressed condition at 14°C. A 0.5% SGRDW’ day?1 was obtained by ~565 (O:N = 29) and ~680 (O:N = 23) μg C ind?1 h?1 at 7 and 14°C respectively. A positive and significantly higher SGRDW’, with the lowest feed ration at 7°C compared with a negative SGRDW’ at 14°C (P < 0.05), indicated that storage time can also possibly be prolonged at low temperatures if the mussels are not fed. 相似文献
84.
Helmy M. Youssef Martin Mascher Mohammad A. Ayoub Nils Stein Benjamin Kilian Thorsten Schnurbusch 《Genetic Resources and Crop Evolution》2017,64(5):843-853
Many-grained mutants occurring spontaneously among their less well-endowed field mates may have appeared to early farmers as fortunate twists of fate foreboding wealth and abundance. In domesticated barley, the number of kernel rows in spike can be tripled by recessive mutant alleles at the Six-rowed spike 1 (vrs1) locus that abolish the suppression of lateral spikelet fertility. In another barley row-type, so called intermedium-spike (int), lateral floret size is often intermediate between six-and two-rowed types. Phenotypic and sequence analyses of our intermedium-spike collection revealed that other genes can increase the size of florets and even stimulate occasional grain setting in lateral spikelets. Here, we show that a complete six-rowed phenotype occurs in a diverse panel of intermedium-spike barley carrying wildtype Vrs1 in the presence of the Int-c.a allele of the intermedium spike-c (int-c) gene, previously considered only as a modifier of lateral spikelet fertility. Int-c.a-type alleles had arisen before domestication and are associated with the enlargement of lateral florets in wild barley, suggesting that natural selection/evolution acts towards reduced lateral floret size. Since Int-c.a cannot overcome the suppression of lateral florets in the genomic background of wild barleys, we infer the existence of other gene loci, at which novel alleles or allelic combinations were selected for after domestication, to increase grain number of barley independently of Vrs1. 相似文献
85.
Stein TJ Pellin M Steinberg H Chun R 《Journal of the American Animal Hospital Association》2010,46(6):413-417
Gastrointestinal (GI) lymphoma is the most frequently diagnosed form of lymphoma in the cat and is categorized into two distinct forms based on the size of neoplastic lymphocytes. Treatments for both large- and small-cell GI lymphoma have been described previously; however, multiple chemotherapy protocols were used, a minimal amount of histopathological characterization was provided, and, in most studies, the majority of diagnoses were obtained via endoscopic pinch biopsies. Twenty-eight cats (24 with full-thickness intestinal biopsies) were diagnosed with small-cell GI lymphoma and treated with a combination of chlorambucil and glucocorticoids. The majority of cases were strongly CD3+, and many displayed epitheliotropism. The overall clinical response rate was 96%, with a median clinical remission duration of 786 days. Follow-up identified seven cats with relapsed disease-all of which were treated with a rescue protocol of cyclophosphamide and glucocorticoids; the response rate was 100%, and four of the 28 cats were diagnosed with a second malignancy. 相似文献
86.
Two experiments were conducted to determine the apparent total tract digestibility (ATTD) of P and the concentration of DE and ME in enzyme-treated soybean meal (SBM) and in conventional soybean meal (SBM-CV). Phosphorus digestibility in 2 enzyme-treated SBM (HP-310 and HP-340) and in SBM-CV was measured using 36 barrows (initial BW: 21.9 ± 1.1 kg) that were housed in metabolism cages and randomly allotted to 6 diets with 6 replicates per diet. During production, HP-310 had been treated with an enzyme mixture containing no phytase, whereas HP-340 was treated with an enzyme mixture that contained exogenous phytase. Three diets containing HP-310, HP-340, or SBM-CV as the sole source of P were formulated. Three additional diets also contained HP-310, HP-340, and SBM-CV, but each of these diets was fortified with 500 units of microbial phytase. The ATTD of P in HP-310 and SBM-CV increased (P < 0.05) as phytase was included in the diet (from 59.8 to 77.7% for HP-310 and from 65.5 to 79.5% for SBM-CV), but the ATTD of P in HP-340 without and with phytase was not different (P > 0.05; 83.8 and 87.7%, respectively). There were no differences (P > 0.05) in the ATTD of P between HP-310 and SBM-CV, but the ATTD of P in HP-340 was greater (P < 0.05) than in the other 2 meals. The DE and ME in corn, 2 sources of enzyme-treated SBM (HP-200 and HP-310), and in SBM-CV were measured in the second experiment using 28 barrows housed in metabolism cages (initial BW: 16.8 ± 2.5 kg of BW). The process used to produce HP-200 is similar to that used to produce HP-310 except that HP-200 is exposed to the enzymes for a shorter period of time than HP-310. A corn-diet consisting of 96.45% corn and vitamins and minerals was formulated. Three additional diets were formulated by mixing corn and each source of SBM with vitamins and minerals. Pigs were randomly allotted to the 4 diets with 7 replicate pigs per diet, and urine and feces were collected quantitatively during the last 5 d of a 14-d feeding period. The concentration of DE in HP-200, HP-310, and SBM-CV was 4,333, 4,316, and 4,347 kcal/kg of DM, respectively. These values were not different (P > 0.05), but they were greater (P < 0.05) than the DE in corn (3,891 kcal/kg of DM). The concentration of ME was 3,780, 3,926, 3,914, and 3,980 kcal/kg of DM in corn, HP-200, HP-310, and SBM-CV, respectively. These values were not different (P > 0.05). It is concluded that enzyme treatment of SBM does not influence the digestibility of P or the concentration of DE and ME in the meals. 相似文献
87.
This article presents an expert support model for in situ soil remediation. It combines knowledge andexperiences obtained from previous in situ soilremediations. The aim of this model is to optimiseknowledge transfer among the various parties involvedin contaminated site management. Structured KnowledgeEngineering (SKE) has been used as a framework formodel development. This approach requires scrutinisingall relevant data to answer questions related to anin situ soil remediation operation. Moreover, itclarifies the roles of the different involved parties.The approach was applied to a chlorinated hydrocarbonpollution at a dry cleaner's. Use of the expertsupport model resulted in the development andselection of a new remediation technique. 相似文献
88.
J L Carpenter B S Stein N W King Y D Dayal F M Moore 《Journal of the American Veterinary Medical Association》1990,197(2):240-242
A chordoma within the deep musculature adjacent to C3 and C4 was excised from a 14-year-old castrated domestic cat. Metastatic chordoma developed in a prescapular lymph node 10 months later. At necropsy 11 months after complete excision of the primary tumor, metastases were found in both retropharyngeal lymph nodes. 相似文献
89.
Y Taura E Stein Y Mullen 《Nippon juigaku zasshi. The Japanese journal of veterinary science》1990,52(6):1163-1170
Ultraviolet (UV)-irradiation of peripheral blood lymphocytes (PBL) of miniature swine prevented them from initiating proliferative responses in allogeneic mixed lymphocyte reactions (MLR). When pigs were given 4 weekly intravenous transfusions of UV-irradiated allogeneic donor PBL differing in major histocompatibility (MHC), PBL of recipient pigs progressively responded less vigorously to donor PBL in MLRs over the treatment period. These pigs did not produce anti-donor PBL antibody. Pigs treated with UV-irradiated PBL also had negligible delayed type hypersensitivity (DTH) responses to donor PBL at the end of the treatment period. In contrast, pigs receiving injections of untreated allogeneic PBL gave strong DTH responses to donor PBL, high proliferation in MLRs with donor PBL and all produced anti-donor PBL antibody. 相似文献
90.